﻿package org.asclub.display
{
      
   import flash.display.BitmapData;
   import flash.display.BlendMode;
   import flash.display.DisplayObject;
   import flash.display.Sprite;
  
   import flash.geom.ColorTransform;
   import flash.geom.Matrix;
   import flash.geom.Point;
   import flash.geom.Rectangle;
  
   /**
    * 此类用于碰撞检测
    */
   public class HitTest
   {

	   /**
		* 计算显示对象，以确定target1是否与target2显示对象重叠或相交。
		* @param	target1   显示对象1
		* @param	target2   显示对象2
		* @param	accuracy  精度
		* @return   Boolean   target1是否与target2显示对象重叠或相交
		*/
		public static function complexHitTestObject( target1:DisplayObject, target2:DisplayObject, accuracy:Number = 1 ):Boolean
		{
				 return complexIntersectionRectangle( target1, target2, accuracy ).width != 0;
		}
	   
		/**
		 * 获取两个显示对象的交集区域
		 * @param	target1   显示对象1
		 * @param	target2   显示对象2
		 * @return  
		 */
		public static function intersectionRectangle( target1:DisplayObject, target2:DisplayObject ):Rectangle
		{
				 // If either of the items don't have a reference to stage, then they are not in a display list
				 // or if a simple hitTestObject is false, they cannot be intersecting.
				 if( !target1.root || !target2.root || !target1.hitTestObject( target2 ) ) return new Rectangle();
				
				 // Get the bounds of each DisplayObject.
				 var bounds1:Rectangle = target1.getBounds( target1.root );
				 var bounds2:Rectangle = target2.getBounds( target2.root );
				
				 // Determine test area boundaries.
				 var intersection:Rectangle = new Rectangle();
				 intersection.x = Math.max( bounds1.x, bounds2.x );
				 intersection.y = Math.max( bounds1.y, bounds2.y );
				 intersection.width    = Math.min( ( bounds1.x + bounds1.width ) - intersection.x, ( bounds2.x + bounds2.width ) - intersection.x );
				 intersection.height = Math.min( ( bounds1.y + bounds1.height ) - intersection.y, ( bounds2.y + bounds2.height ) - intersection.y );
	   
				 return intersection;
		}
	   
		/**
		 * 获取两个显示对象的复合交集区域
		 * @param	target1
		 * @param	target2
		 * @param	accurracy   精度
		 * @return
		 */
		public static function complexIntersectionRectangle( target1:DisplayObject, target2:DisplayObject, accurracy:Number = 1 ):Rectangle
		{                  
				 if( accurracy <= 0 ) throw new Error( "ArgumentError: Error #5001: Invalid value for accurracy", 5001 );
				
				 // If a simple hitTestObject is false, they cannot be intersecting.
				 if( !target1.hitTestObject( target2 ) ) return new Rectangle();
				
				 var hitRectangle:Rectangle = intersectionRectangle( target1, target2 );
				 // If their boundaries are no interesecting, they cannot be intersecting.
				 if(hitRectangle.width * accurracy < 1 || hitRectangle.height * accurracy < 1) return new Rectangle();
				
				 var bitmapData:BitmapData = new BitmapData( hitRectangle.width * accurracy, hitRectangle.height * accurracy, false, 0x000000 );

				 // Draw the first target.
				 bitmapData.draw( target1, HitTest.getDrawMatrix( target1, hitRectangle, accurracy ), new ColorTransform( 1, 1, 1, 1, 255, -255, -255, 255 ) );
				 // Overlay the second target.
				 bitmapData.draw( target2, HitTest.getDrawMatrix( target2, hitRectangle, accurracy ), new ColorTransform( 1, 1, 1, 1, 255, 255, 255, 255 ), BlendMode.DIFFERENCE );
				
				 // Find the intersection.
				 var intersection:Rectangle = bitmapData.getColorBoundsRect( 0xFFFFFFFF,0xFF00FFFF );
				
				 bitmapData.dispose();
				
				 // Alter width and positions to compensate for accurracy
				 if( accurracy != 1 )
				 {
						   intersection.x /= accurracy;
						   intersection.y /= accurracy;
						   intersection.width /= accurracy;
						   intersection.height /= accurracy;
				 }
				
				 intersection.x += hitRectangle.x;
				 intersection.y += hitRectangle.y;
				
				 return intersection;
		}
	   
	   
		protected static function getDrawMatrix( target:DisplayObject, hitRectangle:Rectangle, accurracy:Number ):Matrix
		{
				 var localToGlobal:Point;;
				 var matrix:Matrix;
				
				 var rootConcatenatedMatrix:Matrix = target.root.transform.concatenatedMatrix;
				
				 localToGlobal = target.localToGlobal(new Point());
				 matrix = target.transform.concatenatedMatrix;
				 matrix.tx = localToGlobal.x - hitRectangle.x;
				 matrix.ty = localToGlobal.y - hitRectangle.y;
				
				 matrix.a = matrix.a / rootConcatenatedMatrix.a;
				 matrix.d = matrix.d / rootConcatenatedMatrix.d;
				 if( accurracy != 1 ) matrix.scale( accurracy, accurracy );
				 return matrix;
		}

    }//end of class
} 